Comparison between the PMOD TSI composite series (black circles for daily values and solid orange line for 180-day running mean values) and TSI series reconstructed (red circles for daily values and dashed ciel line for 180-day running mean values) from RPS Ca II K and RPS red observations processed with the methods by Brandt & Steinegger (1998, panel a), Puiu (2019, panel b), Walton et al. (1998, panel c), and Worden et al. (1998, panel d). The PMOD TSI composite was taken as reference for all those reconstructions. Find more details in Section 5. At the bottom of each panel, the corresponding difference between the PMOD TSI and the reconstructed TSI is shown (black circles for daily values and orange line for the 180-day running mean).